From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751091AbWDUJSE (ORCPT ); Fri, 21 Apr 2006 05:18:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751097AbWDUJSE (ORCPT ); Fri, 21 Apr 2006 05:18:04 -0400 Received: from smtp.osdl.org ([65.172.181.4]:35530 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1751091AbWDUJSD (ORCPT ); Fri, 21 Apr 2006 05:18:03 -0400 Date: Fri, 21 Apr 2006 02:17:02 -0700 From: Andrew Morton To: Jens Axboe Cc: linux-kernel@vger.kernel.org, torvalds@osdl.org, davem@davemloft.net Subject: Re: [PATCH] sys_vmsplice Message-Id: <20060421021702.20049dcd.akpm@osdl.org> In-Reply-To: <20060421080239.GC4717@suse.de> References: <20060421080239.GC4717@suse.de> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jens Axboe wrote: > > ... > > sys_splice() moves data to/from pipes with a file input/output. sys_vmsplice() > moves data to a pipe, with the input being a user address range instead. > > ... > > +static void *user_page_pipe_buf_map(struct file *file, > + struct pipe_inode_info *pipe, > + struct pipe_buffer *buf) > +{ > + return kmap(buf->page); > +} > + > +static void user_page_pipe_buf_unmap(struct pipe_inode_info *pipe, > + struct pipe_buffer *buf) > +{ > + kunmap(buf->page); > +} All these new kmaps and kunmaps hurt. It's supposed to be kinda-deprecated and scales poorly. Oh well. > - while (i < nr_pages) > - page_cache_release(pages[i++]); > + while (i < spd->nr_pages) > + page_cache_release(spd->pages[i++]); grumble. I'm going to march over there and take away your `i' key. Or make it emit "page_nr". > +static long do_vmsplice(struct file *file, void __user *buffer, size_t len, > + unsigned int flags) > +{ > + unsigned long uaddr = (unsigned long) buffer; > + struct pipe_inode_info *pipe; > + struct page *pages[PIPE_BUFFERS]; > + unsigned int nr_pages; > + struct splice_pipe_desc spd = { > + .pages = pages, > + .len = len, > + .flags = flags, > + .ops = &user_page_pipe_buf_ops, > + }; > + > + pipe = file->f_dentry->d_inode->i_pipe; > + if (unlikely(!pipe)) > + return -EBADF; > + > + spd.offset = uaddr & ~PAGE_CACHE_MASK; > + nr_pages = (len + spd.offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; Can I feed this 16TB of memory? If so, we just overflowed `nr_pages'. > --- a/include/asm-powerpc/unistd.h > +++ b/include/asm-powerpc/unistd.h > @@ -303,8 +303,9 @@ #define __NR_ppoll 281 > #define __NR_unshare 282 > #define __NR_splice 283 > #define __NR_tee 284 > +#define __NR_vmsplice 285 > > -#define __NR_syscalls 285 > +#define __NR_syscalls 286 > Every time we do this the spufs build breaks: long spu_sys_callback(struct spu_syscall_block *s) { long (*syscall)(u64 a1, u64 a2, u64 a3, u64 a4, u64 a5, u64 a6); BUILD_BUG_ON(ARRAY_SIZE(spu_syscall_table) != __NR_syscalls);